Models of synaptic vesicle endocytosis. (A) In clathrin-based endocytosis, synaptic vesicles collapse fully into the plasma membrane, before being retrieved via a slow process (taking about 10–20 s) mediated by the coat protein clathrin. This occurs at sites distant from the site of fusion. (B) Watanabe et al. propose a new ultrafast mechanism for synaptic vesicle recycling. This process takes roughly one tenth of a second (or less) and involves the formation of large endocytic ‘pits’ devoid of a clathrin coat. Note that both (A) and (B) require the GTPase dynamin to pinch off newly formed endocytic vesicles from the plasma membrane. (C) In the ‘kiss-and-run’ model, synaptic vesicles form a transient pore through which they release their neurotransmitter contents, and are then rapidly recycled (in about a second) at the site of fusion without being absorbed into the membrane.